Bildung, Kristallstruktur und absolute Konfiguration von (−)‐ N ‐(Chloromethyl)galanthaminium‐chlorid

Formation, X‐Ray Crystal Structure, and Absolute Configuration of (−)‐ N ‐(Chloromethyl)galanthaminium Chloride The acetylcholinesterase inhibitor galanthamine ( 1 ), main alkaloid of several Narcissus species, readily forms a quaternary ammonium salt by reaction with the solvent CH 2 Cl 2 . The structure and absolute configuration of (−)‐ N ‐(chloromethyl)galanthaminium chloride ( 2 ) were determined by X‐ray diffraction ( R = 0.075 for 2775 observed independent reflexions) and NMR spectroscopy. The tetragonal crystals (space group P 4 3 ) contain two crystallographically independent cations which do not differ significantly from one another. The CH 2 Cl group is attached to the quaternary N‐atom in stereospecific ( R )‐configuration. In the crystal, the configurational position of the Me group at the N‐atom of 2 differs from that of the crystalline free base 1 . Hydrogen bonding is observed from the OH group at C(3) of 2 to the Cl − anion or to the Cl‐atom of an adjacent cation.